Arabic copied from PDFs, scans and older systems often comes out broken: letters that don't join, words in reverse order, لا turned into ال, or stray diacritics and tatweel. Paste the text, choose the fixes, and copy the clean result.
Many PDFs store Arabic as display shapes or in visual order. Fix broken letters turns display shapes back into normal letters, and Text is reversed puts the letters back in reading order.
It deletes the short-vowel marks (fatha, damma, kasra, shadda, sukun, tanween) so text is easier to search and compare.
Only for searching or matching lists, such as cleaning names in a spreadsheet. It changes the spelling, so don't use it for documents you send.
No. Everything is done in your browser.